Circuit for operating multiple position display devices

ABSTRACT

The circuit of the invention is adapted for operating multipleposition display devices having several groups of display cathode segments or elements positioned in a row, with corresponding segments in each group connected in common, an anode electrode associated with each group of display segments, and an auxiliary electrode being common to and electrically isolating the groups of segments. The cathode segments, together with an anode, can be selectively energized to display a character at any desired cathode group or position and the auxiliary electrode inhibits electrical discharge between the cathode segments and any other than the associated anode. The circuit includes a separate driver circuit for each cathode and for each anode and a circuit for biasing the &#39;&#39;&#39;&#39;OFF&#39;&#39;&#39;&#39; cathodes, the &#39;&#39;&#39;&#39;OFF&#39;&#39;&#39;&#39; anodes, and the auxiliary screen electrode a predetermined difference in potential from the anode supply voltage and independent of the amount of current conducted by the cathodes or by the auxiliary electrode itself.

United States Patent [191 Holz et al.

[ 51 Dec. 18, 1973 CIRCUIT FOR OPERATING MULTIPLE POSITION DISPLAYDEVICES Inventors: George Ernest Holz, North Plainfield; FelixDieterman, Piscataway, both of NJ.

Primary ExaminerCarl D. Quarforth Assistant Examiner.l. M. PotenzaAttorney-George L. Kensinger et a1.

[ 5 7 ABSTRACT The circuit of the invention is adapted for operatingmultiple-position display devices having several groups of displaycathode segments or elements positioned in a row, with correspondingsegments in each group connected in common, an anode electrodeassociated with each group of display segments, and an auxiliaryelectrode being common to and electrically isolating the groups ofsegments. The cathode segments, together with an anode, can beselectively energized to display a character at any desired cathodegroup or position and the auxiliary electrode inhibits electricaldischarge between the cathode segments and any other than the associatedanode. The circuit includes a separate driver circuit for each cathodeand for each anode and a circuit for biasing the OFF cathodes, the OFFanodes, and the auxiliary screen electrode a predetermined difference inpotential from the anode supply voltage and independent of the amount ofcurrent conducted by the cathodes or by the auxiliary electrode itself.

20 Claims, 3 Drawing Figures r34- 41 3; 51 36 4 1 5 ,i .L J: Ebb ,l;| 1-1] I H21 AF 12 140 43 1 0 53,1 (03 w, I12 :I :Z/ 111 2 7 113 25 PAIENIEDEM 3.780.341

SHEEI 1 i 2 2 0 .42 41 45 I40 52 5| 5 I (02. (pl QB O IN'VENTOR. GEORGEE. HOLZ BY FE'LlX D1ETERMHN QTTORNEY CIRCUIT FOR OPERATING MULTIPLEPOSITION DISPLAY DEVICES This application is a continuation of Ser. No.85,622,-

filed Oct. 30, 1970, now abandoned.

BACKGROUND OF THE INVENTION This invention relates to apparatus foroperating glow discharge display devices having multiple displaypositions. More particularly, the invention relates to circuitry foroperating multiple-position gas discharge devices having segmentedcathode electrodes.

Several display devices have been developed recently having a pluralityof groups of cathode segments positioned in a row in either a tube or aflat panel. These devices generally include electrical connectionsbetween the corresponding cathode segments, and an anode for eachdisplay position to enable a timesharing mode of operation.

In operating such devices, the cathode segments are selectivelyenergized, together with an anode, to provide an electrical discharge ata selected group of cathode segments to display a desired number orsymbol. The electrical discharge ionizes the adjacent gas molecules andresults in cathode glow discharge on the selected segments which displaythe desired character.

, The electrical discharge between the selected groups of displaysegments and the associated anodes must be isolated from affecting theON or OFF state of the other groups of display segments and theirrespective anodes. When one group of electrode segments is glowing andrepresenting a character, however, undesirable spurious glow sometimesdevelops in an adjacent group of electrodes or in a path or positivecolumn arising between them.

This spurious discharge and the resultant spurious glow can be overcomeby providing an auxiliary electrode biased inter intermediate thecathode and anode potential as described and claimed in Harvey, et al.,U.S. Pat. application Ser. No. 78,045 filed Oct. 5, 1970, and nowabandoned. The auxiliary electrode, however, conducts current from theionized gas in the device which raises its potential in proportion tothe number of cathode segments which are energized.

The potential on the auxiliary electrode, however, must be keptsufficiently more negative than the ON anode in order to preventspurious cathode glow but without initiating cathode glow on theauxiliary electrode itself. One level of bias on the auxiliary electrodeis sometimes ineffective to prevent spurious discharge both when onlyone or two segments are energized and also when all or most of thecathodes are energized. This difficulty becomes especially pronouncedwhen variations in tubes or panels result in them having differentoperating characteristics.

Another difficulty experienced in operating such display devices is anunsuitably narrow range or tolerance to variation in the anode supplyvoltage and in the auxiliary electrode bias voltage for effectivespurious glow suppression.

SUMMARY OF THE INVENTION Accordingly, an object of this invention is toimprove spurious glow supporession in multiple-position display deviceshaving commonly connected cathode electrodes.

Another object of the invention is to enlarge the range or tolerance forbias levels in multiple-position gas discharge display devices havingauxiliary electrodes for spurious glow suppression.

A further object of the invention is to reduce the complexity and costof systems for operating display devices having spurious glowsuppression electrodes.

According to the invention a circuit for operating multiple-positiondisplay devices includes voltage reference elements or devices coupledfor establishing predetermined potential differences between the anodesupply voltage and the unenergized cathodes and anodes and the auxiliaryelectrode. It also includes an impedance coupled to the auxiliaryelectrode and to its voltage reference element or device for conductingthe leakage current that it collects from ON anodes, without affectingthe bias potential on it.

DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view of a segmented cathodedisplay tube having individual anodes and an overlying auxiliaryelectrode;

FIG. 2 is an elevational view of a longitudinal section of the displaytube or panel of FIG. 1; and

FIG. 3 is an electrical schematic diagram of a preferred embodiment ofthe circuit of applicants invention for operating such a device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principles of the inventionare particularly applicable to the type of display device described andclaimed in copending Harvey, et al., U.S. Pat. application Ser. No.78,045, filed Oct. 5, 1970. Some of the features of such a tube 10 areshown schematically in FIGS. 1 and 2 of three representative displaypositions. A plurality of groups of cathode segments 41-47, 51-57,61-67, etc. are connected to corresponding conductors 21-27 which areinsulated from each other and isolated from glow, and an anode electrode140, 150, 160, etc. is provided for each group. The anodes in FIG. 1 areeach shown as a ring surrounding its group of cathodes, but it may be ascreen covering the associated cathode group, or it may take any othershape. In addition, the device includes a screen electrode 230 which isdisposed above the groups; of cathodes and anodes and is electricallyassociated with them all and top and bottom insulating plates 200 and20, respectively.

Briefly, in operation of the tube shown in FIGS. 1 and 2, drive signalsare applied to the cathodes via conductors 21, 22, 27 in accordance withthe input information. Simultaneously, each of the anodes is energizedin turn or in any other desired order or sequence via leads 34, 35, 36,etc. to cause the cathodes in its group to exhibit cathode glow. Screenelectrode 230 carries a suitable potential applied to lead 235 forpreventing spurious glow between adjacent display positions.

The preferred embodiment of the circuit of the invention is illustratedin FIG. 3 and display device 10 is shown schematically. Display cathodesegments 41, 51 and 61 are connected to conductor 21 which is connectedto the collector of cathode driver transistor 121. Display cathodesegments 42, S2, and 62 are connected to conductor 22 which is connectedto the collector of driver transistor 122. The cathode segments 43, 53,and 63 are connected to conductor 23 which is connected to the collectorof cathode drive 123. Currentlimiting resistors 131, 132 and 133 areconnected between the emitters of transistors 121, 122 and 123,respectively, and reference potential terminal 120. The base electrodesof cathode driver transistors 121, 122 and 123 are connected to inputterminals 221, 222, 223, respectively, for receiving positive-goinginformation signals.

Anode lead 34 of anode 140 is connected to the collector of anode drivetransistor 240. Anode lead 35 of anode 150 is connected to the collectorof transistor switch 250. Anode lead 36 of anode 160 is connected to thecollector of anode switch 260. The emitter electrodes of anodetransistor switches 240-260 are connected to anode supply terminal 12and their base electrodes are connected to anode control terminals 245,255 and 265 by current-limiting resistors 241, 251 and 261,respectively, for receiving negative-going control signals.

The cathode segments are initially biased by pull-up resistors 111, 112and 113 connected at one end to the collectors of cathode drivertransistors 121, 122 and 123, respectively. The other ends of resistors111-113 are connected at circuit junction 15 to the anode of Zener diode14, the cathode of which is connected to anode supply terminal 12.Anodes 140-160 are initially biased by resistors 340-360 also connectedat junction 15 to the anode of Zener diode 14. This establishes a fixedpotential difference between the anode supply voltage Ebb and theunenergized cathodes and anodes, regardless of the specific value of Ebbor of fluctuation in it.

The electrode terminal 235 of auxiliary electrode 230 is connected atcircuit junction 17 to the anode of Zener diode 16 and to one end ofresistor 18. The cathode of Zener diode 16 is connected at junction 15to the anode of reference diode 14 and the other end of resistor 18 isconnected to reference potential terminal 120. This establishes aconstant difference in potential between the auxiliary electrode 230 andthe anode supply potential Ebb and auxiliary electrode current isconducted by resistor 18 to source Ek to be connected to terminal 120.Reference diodes 14 and 16 may alternatively be any other type ofvoltage regulating devices or may be voltage sources. Resistor 18 may bereplaced with any other current-limiting impedance, either an active orpassive device.

In operation of the device, the auxiliary electrode 230 conducts aleakage current from whichever anode electrode 140-160 is energized toresistor 18 and the source connected to terminal 120. If this leakagecurrent increases as more cathodes are energized, for example, thecurrent through Zener reference diodes 14 and 16 merely decreases,without affecting the potential on either the OFF cathodes or anodes oron the auxiliary electrode itself. As the leakage current of auxiliaryelectrode 230 decreases due to decreased glow discharge, for example,the Zener diode current simply increases, also without affecting thebias potentials on the electrodes of the device.

The maintenance of the voltage difference between auxiliary electrode230 and the anode supply voltage prevents the auxiliary electrode frombecoming too greatly cathodic (too negative with respect to an energizedanode) which may cause it to develop cathode glow itself. It alsoprevents auxiliary electrode 230 from rising in potential closer to theON" anode potential as a larger number of cathode segments areenergized,

and thus lose its spurious glow suppression effectiveness.

In the operation of display device 10 to display a plurality ofnumerals, relatively negative information signals are applied to one ormore cathode conductors 21, 22, 23 27 from a suitable data source, and agenerally positive potential may be applied to the first anode 140. Theselected ones of cathode segments 41-47 which are thus energized, glowand display a first numeral at the first display position. A secondgroup of information signals is applied to selected cathode conductors21-27 and the second anode is energized, and a second numeral isdisplayed by the selected ones of cathode segments 51-57 at the seconddisplay position. In the same way, the successive application ofdifferent information signals to selected cathode conductors and to theanodes, in turn, causes a character to be displayed at each characterposition. If this sequence is repeated through the display device fromone end to the other at a sufficiently high rate, a stationary butchangeable series of numerals can be displayed in the panel, one at eachcharacter position. As the cycling operation is carried out, if theinformation signals on the cathode conductors change, then thecharacters at the respective display positions also change.

The above-described mode of operation utilizes sequential time-shareddriving of anode electrodes 140, 150, 160, etc., of the device. Thissequentially energizes the successive display positions along thedevice. Another mode of operation involves time-shared driving of thecathode electrode segments. The anode electrodes 140, 150, 160, etc.,are selectively energized from a data source, for example, and cathodeconnectors 21-27 are energized successively for sequencing the display.The energization of the anode electrodes 140, 150, 160, etc., may bechanged as desired for varying the pattern of the display. The anodesand cathodes may be energized in any other desired order, also,depending upon the desired mode of display.

Although the preferred embodiment of the invention has been described indetail, it should be understood that the present disclosure has been byway of example only. Many modifications and variations of the inventionare possible in light of the above teachings. It is, therefore, to beunderstood that the invention may be practiced otherwise than asspecifically disclosed.

What We Claim is:

l. A character display circuit comprising an envelope containing anionizable gas,

an anode and a plurality of cathodes within said envelope, each of saidcathodes having the shape of a segment of a character to be displayed,

circuit means for establishing a glow potential between said anode anddifferent combinations of said cathodes for causing said differentcombinations of said cathodes to glow and thereby display differentcharacters,

said circuit means including a plurality of cathode drivers, oneconnected to each of said cathodes, and means for selectively energizingsaid cathode drivers to render different combinations of their connectedcathodes glowing,

an auxiliary electrode in contact with the ionizable gas and inoperative relation with said anode and cathodes,

an anode supply voltage terminal and circuit means connected betweensaid terminal and said anode,

bias circuit means for said anode and said cathodes including a voltagereference device connected electrically from said anode supply voltageterminal and having a second terminal to establish a predeterminedvoltage on said second terminal relative to the voltage on the anodesupply terminal, and a plurality of impedance means, one connected fromsaid second terminal to said anode and the others each connected fromsaid second terminal to a different one of said cathodes, and

second bias circuit means for establishing a bias voltage on saidauxiliary electrode comprising a second voltage reference deviceconnected between said anode supply terminal and a third terminal toestablish a voltage thereon lower than the voltage on said secondterminal, and circuit means connecting said auxiliary electrode to saidthird terminal.

2. A character display device as in claim 1 wherein the second voltagereference device is connected between said second and third terminals,and it is thus connected to the anode supply voltage terminal throughsaid first reference voltage device.

3. A character display circuit as in claim 2 further including a cathodereference terminal,

a plurality of current-limiting impedance devices,

one connected from said cathode reference terminal to each of saidcathode drivers, and

a further impedance device connected between said cathode referenceterminal and said third terminal.

4. A character display circuit comprising an envelope containing anionizable gas,

an anode and a plurality of cathodes within said envelope, each of saidcathodes having the shape of a segment of a character to be displayed,

circuit means for establishing a glow potential between said anode anddifferent combinations of said cathodes for causing said differentcombinations of cathodes to glow and thereby display differentcharacters,

said circuit means including'a plurality of cathode drivers, oneconnected to each of said cathodes, and means for selectively energizingsaid cathode drivers to render different combinations of their connectedcathodes glowing,

an auxiliary electrode in contact with the ionizable gas and inoperative relation with said anode and cathodes,

bias circuit means for said anode and cathodes including a firstterminal at a predetermined voltage, an impedance'connected from saidfirst terminal to said anode, and a plurality of additional impedanceseach connected from said first terminal to a different one of saidcathodes, and

second bias circuit means for said auxiliary electrode including avoltage reference device connected electrically from said first terminalto a second terminal, and circuit means connecting said auxiliaryelectrode to said second terminal.

5. A character display circuit as in claim 4 further including 6. Acharacter display circuit for displaying any one of a plurality ofcharacters in each of a plurality of sideby-side character positions,comprising a plurality of cathode conductors each electrically connectedto one of the cathodes in each character position,

a plurality of cathode drivers, each connected to one of said cathodeconductors, for energizing said cathodes selectively in response to afirst set of input signals,

anode selection circuit means for selectively energizing said anodes, insynchronism with the selective energization of said cathodes, inresponse to a second set of input signals, for displaying selectedcharacters in each of said character positions,

an auxiliary electrode in the gaseous atmosphere associated with eachcharacter position, the current therethrough being a function of thenumber of cathodes which are glowing,

an anode voltage supply terminal, with said anode selection circuitmeans connected between said terminal and each of said anodes,

anode bias circuit means including a second terminal, first voltagereference means including a voltage reference device connected from saidanode supply voltage to said second terminal, and a plurality ofimpedance devices, each connected from said second terminal to one ofsaid anodes, and

an auxiliary bias circuit means including a second voltage referencemeans connected from said anode supply voltage terminal to a thirdterminal and circuit means connecting said auxiliary electrode to saidthird terminal,

7. A character display circuit as in claim 6 wherein said second voltagereference means includes a voltage reference device connected from thesecond to the third terminal.

8. A character display circuit as in claim 6 further including a ctahodebias circuit including a further plurality of impedance devices, eachconnected from said second terminal to one of said cathode conductors.

9. A character display circuit for displaying any one of a plurality ofcharacters in each of a plurality of sideby-side character positions,comprising a plurality of anodes, one in each of said characterpositions,

a plurality of groups of cathodes, each group being associated with oneof said anodes and being located in one of said character positions,each of the cathodes having the shape of a segment of one of thecharacters to be displayed,

each of said anodes and its associated cathodes being disposed in anionizable gas atmosphere capable of sustaining cathode glow discharge,

a plurality of cathode conductors each electrically connected to one ofthe cathodes in each character position,

a plurality of cathode drivers, each connected to one of said cathodeconductors, for energizing said cathodes selectively in responseo to afirst set of input signals,

anode selection circuit means for selectively eeergizing said anodes, insynchronism with the selective energization of said cathodes, inresponse to a second set of input signals, for displaying selectedcharacters in each of said character positions,

an auxiliary electrode in the gaseous atmosphere associated with eachcharacter position,

anode bias circuit means including a first terminal at a predeterminedpotential and a plurality of impedance devices each connected from saidterminal to one of said anodes, and

an auxiliary electrode bias circuit including a voltage reference deviceconnected electrically from said first terminal to said auxiliaryelectrode.

10. A character display circuit as in claim 9 further comprising acathode bias circuit including a further plurality of impedance deviceseach connected from said first terminals to one of said cathodeconductors.

11. A character display circuit as in claim 9 further comprising ananode supply voltage terminal, with said anode selection circuit meanselectrically connecting said terminal to each of said anodes, and

a voltage reference device electrically connected from said anode supplyvoltage terminal to said first terminal.

12. A character display circuit for displaying any one of a plurality ofcharacters in a plurality of side-by-side character positions,comprising an envelope formed of a front plate with a viewing window anda rear plate, said plates being sealed together along a predeterminedperimeter surrounding the side-by-side character positions to establisha gas tight enclosure,

an ionizable gas within said enclosure at a pressure capable ofsustaining a cathode glow discharge,

a plurality of anodes, one at each of said character positions withinsaid envelope,

a plurality of groups of cathodes, each such group being associated withone of said anodes and being located in one of said character positions,each of the cathodes having the shape of a segment of one of thecharacters to be displayed,

a plurality of elongated conductors extending within said envelope, eachelectrically connected to one of the cathodes in each characterposition, and each connected electrically to a terminal outside saidenvelope for connection to an external circuit,

insulating material separating each of said conductors from all of thecathodes except the cathode in each character position to which it isconnected,

anode selection means for energizing said anodes sequentially andcathode selection means for selectively energizing differentcombinations of said cathode conductors sequentially, in synchronismwith sequential energization of the anodes, to form a side-by-sidecharacter display along said character positions,

an auxiliary electrode associated with each of said character positionsand being in operative relation with the anode and the cathodes in eachsuch position, anode bias circuit means including a first terminal at apredetermined potential and a plurality of impedance means eachconnected electrically from said first terminal to a different one ofsaid anodes,

cathode bias circuit means including a further plurality of impedancemeans each connected electrically from said first terminal to adifferent one of said cathodes, and

a voltage reference device connected electrically from said firstterminal to said auxiliary electrode.

13. A character display circuit as in claim 12 wherein the auxiliaryelectrode has a portion thereof located between the anode and cathodesin each character position and those of the next adjacent characterposition,

further including an anode voltage supply terminal connected throughsaid anode selection circuit to each of said anodes and a furtherreference voltage device connected from said anode voltage supplyterminal to bias the auxiliary electrode to a predetermined voltagebelow said anode supply voltage for isolating the anode and cathodes ofeach character position from those of all of the other characterpositions.

14. A system for operating multiple-position display devices having aplurality of groups of cathode elements situated in an ionizable medium,an anode associated with each of the groups, and an auxiliary electrodethat is common to all of the groups and shields them from each other,comprising means coupled to each of the cathode elements for drivingthem selectively in response to a first set of input signals,

means coupled to each of the anodes for energizing them selectively inresponse to a second set of input signals,

voltage supply terminals connected to the cathode driving means and tothe anode energizing means for receiving operating potential for them,

voltage reference means coupled between the auxiliary electrode and thevoltage supply terminal of the anode energizing means, and

impedance means coupled between the voltage reference means and thecathode driver voltage supply terminal.

15. The display system of claim 14 further comprising resistance meansalso coupling each of the cathode elements and each of the anodes tosaid voltage reference means. I

16. The display system of claim 15 wherein the volt age reference meanscomprises a pair of voltage reference devices connected in electricalseries with said impedance means, and said resistance means couples theanodes and cathode elements to the junction of the voltage referencedevices.

17. The display system of claim 14 wherein the groups of cathodeelements comprise a plurality of cathodes in the form of segments of acharacter to be displayed, with corresponding segments of the groupsbeing interconnected and the auxiliary electrode electrically shieldsthe groups of segments from each other for preventing spurious glowdischarge in the device.

18. The display system of claim 17 wherein the anode energizing meanscomprises a voltage switch for each anode, and the anodes and cathodeelements are each 20. The display system of claim 18 wherein the anodedrivers are connected to a source of information signals to control thepattern to be displayed and the cathode drivers are connected to asource of position control signals to select the position for eachdisplay pattern in the device.

1. A character display circuit comprising an envelope containing anionizable gas, an anode and a plurality of cathodes within saidenvelope, each of said cathodes having the shape of a segment of acharacter to be displayed, circuit means for establishing a glowpotential between said anode and different combinations of said cathodesfor causing said different combinations of said cathodes to glow andthereby display different characters, said circuit means including aplurality of cathode drivers, one connected to each of said cathodes,and means for selectively energizing said cathode drivers to renderdifferent combinations of their connected cathodes glowing, an auxiliaryelectrode in contact with the ionizable gas and in operative relationwith said anode and cathodes, an anode supply voltage terminal andcircuit means connected between said terminal and said anode, biascircuit means for said anode and said cathodes including a voltagereference device connected electrically from said anode supply voltageterminal and having a second terminal to establish a predeterminedvoltage on said second terminal relative to the voltage on the anodesupply terminal, and a plurality of impedance means, one connected fromsaid second terminal to said anode and the others each connected fromsaid second terminal to a different one of said cathodes, and secondbias circuit means for establishing a bias voltage on said auxiliaryelectrode comprising a second voltage reference device connected betweensaid anode supply terminal and a third terminal to establish a voltagethereon lower than the voltage on said second terminal, and circuitmeans connecting said auxiliary electrode to said third terminal.
 2. Acharacter display device as in claim 1 wherein the second voltagereference device is connected between said second and third terminals,and iT is thus connected to the anode supply voltage terminal throughsaid first reference voltage device.
 3. A character display circuit asin claim 2 further including a cathode reference terminal, a pluralityof current-limiting impedance devices, one connected from said cathodereference terminal to each of said cathode drivers, and a furtherimpedance device connected between said cathode reference terminal andsaid third terminal.
 4. A character display circuit comprising anenvelope containing an ionizable gas, an anode and a plurality ofcathodes within said envelope, each of said cathodes having the shape ofa segment of a character to be displayed, circuit means for establishinga glow potential between said anode and different combinations of saidcathodes for causing said different combinations of cathodes to glow andthereby display different characters, said circuit means including aplurality of cathode drivers, one connected to each of said cathodes,and means for selectively energizing said cathode drivers to renderdifferent combinations of their connected cathodes glowing, an auxiliaryelectrode in contact with the ionizable gas and in operative relationwith said anode and cathodes, bias circuit means for said anode andcathodes including a first terminal at a predetermined voltage, animpedance connected from said first terminal to said anode, and aplurality of additional impedances each connected from said firstterminal to a different one of said cathodes, and second bias circuitmeans for said auxiliary electrode including a voltage reference deviceconnected electrically from said first terminal to a second terminal,and circuit means connecting said auxiliary electrode to said secondterminal.
 5. A character display circuit as in claim 4 further includingan anode supply voltage terminal, with circuit means connected betweensaid terminal and said anode, and a second voltage reference deviceconnected from said anode supply voltage terminal to said firstterminal.
 6. A character display circuit for displaying any one of aplurality of characters in each of a plurality of side-by-side characterpositions, comprising a plurality of anodes, one in each of saidcharacter positions, a plurality of groups of cathodes, each such groupbeing associated with one of said anodes at one of said characterpositions, each of the cathodes having the shape of a segment of one ofthe characters to be displayed, each of said anodes and its associatedcathodes being disposed in an ionizable gas atmosphere capable ofsustaining cathode glow discharge, a plurality of cathode conductorseach electrically connected to one of the cathodes in each characterposition, a plurality of cathode drivers, each connected to one of saidcathode conductors, for energizing said cathodes selectively in responseto a first set of input signals, anode selection circuit means forselectively energizing said anodes, in synchronism with the selectiveenergization of said cathodes, in response to a second set of inputsignals, for displaying selected characters in each of said characterpositions, an auxiliary electrode in the gaseous atmosphere associatedwith each character position, the current therethrough being a functionof the number of cathodes which are glowing, an anode voltage supplyterminal, with said anode selection circuit means connected between saidterminal and each of said anodes, anode bias circuit means including asecond terminal, first voltage reference means including a voltagereference device connected from said anode supply voltage to said secondterminal, and a plurality of impedance devices, each connected from saidsecond terminal to one of said anodes, and an auxiliary bias circuitmeans including a second voltage reference means connected from saidanode supply voltage terminal to a third terminal and circuit meansconnecting said auxiliary electrodE to said third terminal,
 7. Acharacter display circuit as in claim 6 wherein said second voltagereference means includes a voltage reference device connected from thesecond to the third terminal.
 8. A character display circuit as in claim6 further including a ctahode bias circuit including a further pluralityof impedance devices, each connected from said second terminal to one ofsaid cathode conductors.
 9. A character display circuit for displayingany one of a plurality of characters in each of a plurality ofside-by-side character positions, comprising a plurality of anodes, onein each of said character positions, a plurality of groups of cathodes,each group being associated with one of said anodes and being located inone of said character positions, each of the cathodes having the shapeof a segment of one of the characters to be displayed, each of saidanodes and its associated cathodes being disposed in an ionizable gasatmosphere capable of sustaining cathode glow discharge, a plurality ofcathode conductors each electrically connected to one of the cathodes ineach character position, a plurality of cathode drivers, each connectedto one of said cathode conductors, for energizing said cathodesselectively in responseo to a first set of input signals, anodeselection circuit means for selectively eeergizing said anodes, insynchronism with the selective energization of said cathodes, inresponse to a second set of input signals, for displaying selectedcharacters in each of said character positions, an auxiliary electrodein the gaseous atmosphere associated with each character position, anodebias circuit means including a first terminal at a predeterminedpotential and a plurality of impedance devices each connected from saidterminal to one of said anodes, and an auxiliary electrode bias circuitincluding a voltage reference device connected electrically from saidfirst terminal to said auxiliary electrode.
 10. A character displaycircuit as in claim 9 further comprising a cathode bias circuitincluding a further plurality of impedance devices each connected fromsaid first terminals to one of said cathode conductors.
 11. A characterdisplay circuit as in claim 9 further comprising an anode supply voltageterminal, with said anode selection circuit means electricallyconnecting said terminal to each of said anodes, and a voltage referencedevice electrically connected from said anode supply voltage terminal tosaid first terminal.
 12. A character display circuit for displaying anyone of a plurality of characters in a plurality of side-by-sidecharacter positions, comprising an envelope formed of a front plate witha viewing window and a rear plate, said plates being sealed togetheralong a predetermined perimeter surrounding the side-by-side characterpositions to establish a gas tight enclosure, an ionizable gas withinsaid enclosure at a pressure capable of sustaining a cathode glowdischarge, a plurality of anodes, one at each of said characterpositions within said envelope, a plurality of groups of cathodes, eachsuch group being associated with one of said anodes and being located inone of said character positions, each of the cathodes having the shapeof a segment of one of the characters to be displayed, a plurality ofelongated conductors extending within said envelope, each electricallyconnected to one of the cathodes in each character position, and eachconnected electrically to a terminal outside said envelope forconnection to an external circuit, insulating material separating eachof said conductors from all of the cathodes except the cathode in eachcharacter position to which it is connected, anode selection means forenergizing said anodes sequentially and cathode selection means forselectively energizing different combinations of said cathode conductorssequentially, in synchronism with sequential energization of thE anodes,to form a side-by-side character display along said character positions,an auxiliary electrode associated with each of said character positionsand being in operative relation with the anode and the cathodes in eachsuch position, anode bias circuit means including a first terminal at apredetermined potential and a plurality of impedance means eachconnected electrically from said first terminal to a different one ofsaid anodes, cathode bias circuit means including a further plurality ofimpedance means each connected electrically from said first terminal toa different one of said cathodes, and a voltage reference deviceconnected electrically from said first terminal to said auxiliaryelectrode.
 13. A character display circuit as in claim 12 wherein theauxiliary electrode has a portion thereof located between the anode andcathodes in each character position and those of the next adjacentcharacter position, further including an anode voltage supply terminalconnected through said anode selection circuit to each of said anodesand a further reference voltage device connected from said anode voltagesupply terminal to bias the auxiliary electrode to a predeterminedvoltage below said anode supply voltage for isolating the anode andcathodes of each character position from those of all of the othercharacter positions.
 14. A system for operating multiple-positiondisplay devices having a plurality of groups of cathode elementssituated in an ionizable medium, an anode associated with each of thegroups, and an auxiliary electrode that is common to all of the groupsand shields them from each other, comprising means coupled to each ofthe cathode elements for driving them selectively in response to a firstset of input signals, means coupled to each of the anodes for energizingthem selectively in response to a second set of input signals, voltagesupply terminals connected to the cathode driving means and to the anodeenergizing means for receiving operating potential for them, voltagereference means coupled between the auxiliary electrode and the voltagesupply terminal of the anode energizing means, and impedance meanscoupled between the voltage reference means and the cathode drivervoltage supply terminal.
 15. The display system of claim 14 furthercomprising resistance means also coupling each of the cathode elementsand each of the anodes to said voltage reference means.
 16. The displaysystem of claim 15 wherein the voltage reference means comprises a pairof voltage reference devices connected in electrical series with saidimpedance means, and said resistance means couples the anodes andcathode elements to the junction of the voltage reference devices. 17.The display system of claim 14 wherein the groups of cathode elementscomprise a plurality of cathodes in the form of segments of a characterto be displayed, with corresponding segments of the groups beinginterconnected and the auxiliary electrode electrically shields thegroups of segments from each other for preventing spurious glowdischarge in the device.
 18. The display system of claim 17 wherein theanode energizing means comprises a voltage switch for each anode, andthe anodes and cathode elements are each coupled to said voltagereference means for being pre-biased.
 19. The display system of claim 18in which the cathode drivers are connected to a source of informationsignals to control the pattern to be displayed and the anode drivers areconnected to a source of position control signals to select the positionfor each display pattern in the deivce.
 20. The display system of claim18 wherein the anode drivers are connected to a source of informationsignals to control the pattern to be displayed and the cathode driversare connected to a source of position control signals to select theposition for each display pattern in the device.